Pulverizer with satellite spacer assembly

ABSTRACT

Apparatus is provided for pulverizing raw coal feed stock into comminuted particles which can be conveyed to the combustion chamber of a furnace. A satellite spacer assembly is positioned above the pulverizer table and mounted on the pulverizer rollers such that the rollers are separated from each other to prevent skidding.

1111 3,790,095 1451 Feb. 5, 1974 FOREIGN PATENTS OR APPLICATIONS 201,726

[ PULVERIZER WITH SATELLITE SPACER 8/1955 Australia.............................241/117 ASSEMBLY Robert Paul Gillette, RD. 3, Radtke [76] Inventor:

Rd., Shongum Lake, Randolph, NJ. 07801 Primary Examiner-James L. Jones, Jr. Assistant Examiner-E. F. Desmond [22] Filed:

Apr. 2 1972 Attorney, Agent, or Firm-John Maier, III

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' 4 C ime Dr F E 3,366,338 1/1968 Barton 3,658,264 4/1972 1 WITH SATELLITE SPACE BACKGROUND OF THE INV NTION In connection with the operation of relatively-large coal fired furnaces which are used in vapor generating systems in the utility industry for production of electricity, it is necessary to supply finely powdered coal to the combustion chamber of the furnace. The raw coal feed stock is usually reduced to comminuted particles in a pulverizer apparatus which generally consists of a rotating grinding table on which there is formed a grinding surface, and relatively heavy rollers are journaled within the apparatus and maintained in contact with the grinding surface by a thrust ring.

There has recently developed a major problem in connection with the pulverizing of coal feed stocks containing particles which cannot easily be pulverized by the apparatus, such as iron pyrite and the like. These relatively hard constituents are more commonly found in many types of coal which are being mined today. The hard particles often prevent the pulverizing apparatus from functioning efficiently, in that skidding action is translated to the rollers. In accordance with the present invention, skidding of the rollers has been alleviated'by providing a satellite spacer assembly with radially extending, fixed shafts for rotatably mounting the pulverizer rollers.

By eliminating the vertical center shaft structure which heretofore has been used for mounting roller spacerdevices, it is possible to have the entire center of the pulverizer open for coal flow without any major obstruction thereto. This also results in eliminating theobstruction to the coal flow around the grinding surfaces. The elimination of the center support for the spacer 'means results in a pulverizer structure having a much simpler design than heretofore has been possible, thereby achieving better performance and easier maintenance. Further, the satellite spacer of the present invention has only one major wear part, which is the spherical bearing block that can easily be removed for replacement purposes. Also, there is less frictional drag on the pulverizer rollers by providing a satellite spacer having individual shafts for rotatably mounting the rollers. A still further advantage is achieved 'by inhibiting grinding roller yaw or the swing about the vertical axis of the pulverizer. The instant invention also results in better capacity for the pulverizer through better air flow by removal of the center obstructions. This better air flow lowers the retention time of particles on the grinding table thereby alleviating one of the major causes of pulverizer skidding.

SUMMARY OF-THE INVENTION the table and for introducing the material into the housing in contact with the grinding surface. A plurality of rollers are mounted for rotationabout their respective axes and each of the rollers has a peripheral grinding face maintained incontact with the grinding surface, and a thrust ring is mounted in contact with the rollers.

Positioned above the-table is a spacer center yoke fixed to the center yoke which radially extend outwardly for supporting the center yoke and rotatably mounting the rollers. In this manner, the rollers are separated from each other and are prevented from skidding. A

BRIEF DESCRIPTION OF THE DRAWINGS be more fully appreciated by referring to the following description of a presently preferred but nonetheless illustrative embodiment in accordance with the present invention when taken in connection with the accompanying drawings, wherein: 7

FIG. 1 is a front sectional view of a portion of a pulverizing apparatus embodying features of the present invention;

FIG. 2 is an enlarged sectional view of part of the satellite spacer assembly, showing an enlarged portion of the spacer hub; and I FIG. 3 is an enlargedplan view of the rollers and satellite spacer assembly to better show the mounting arrangement .for the pulverizer rollers.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a pulverizing apparatus is shown which is generally designated by the reference numeral 10. The pulverizing apparatus 10 includes a steel housing 12 which is mounted at groundlevel for enclosing a rotatably mounted grinding unit 14. Raw coal feed stock is introduced into the housing 12 througha conduit system 16 which is generally positioned above the grinding unit 14. j

The grinding unit14 includes a table 20 on which there is mounted aremovable grinding ring 22 formed with an annular groove 24. The table 20 is mounted for rotation on a support shaft25 and is powered by an electric motor which has not been shown in the drawings forthe sake of simplicity.

A plurality of spaced-apart pulverizingg rollers 26, preferably three in number, are mounted for' rotation about their respective axes. Each of the rollers 26 has a peripheral grinding face which is maintained in contact with the outer grinding surface of annular groove 24.- The rollers 26 are also formed with a bearing collar 30 which has an annular groove 32. A thrust ring 34 is mounted in housing 12 above the pulverizing rollers 26, and load is applied by means of compression springs 36. The thrust ring 34 is integrally formed with an annular lip 38 which is configurated in accordance with the outer periphery of annular groove 32 in order to achieve smooth mating contact.

In accordance with the present invention, a satellite spacer assembly 40 is positioned above they grinding ring 22 by means of radially extending shafts 42 on which the rollers 26 are rotatably mounted. The satellite spacer assembly 40 includes an annular yoke section 44 having vertically oriented supports 46 which are integrally fomied with a horizontally positioned support ring plate 48. As best shown in FIGS. 2 and 3, yoke section 44 is formed with through bores 50 for receiving the shafts 42 which are maintained in a fixed position by the welds 52 and gusset plates '54. It should be noted that the yoke section 44 is formed with a frus- 3 toconical configuration for the purpose of mounting the shafts 42 at an acute angle to the vertical, central axis of the yoke section 44. Also, this frustoconical configuration allows for the location of the supports 46 and 48 along the innersurface of the yoke section 44 for improved structural strength, as well as minimizing the obstructions in the center of the pulverizing apparatus 10, thereby obtaining a more efficient flow of pulverized coal and air.

As best shown in FIG. 2, the outer end of shaft 42 is formed with a reduced diameter section 60 which is integrally formed with stepped-down threaded end section 62. The reduced diameter section 60 is provided with a pair of outer keyway slots 64, and each of the outer keyway slots 64 is positioned approximately 180 degrees apart along the circumference of shaft 42. A spherical bearing block 66, having an internal central bore 68, is formed with a pair of inner keyway slots 70 for mounting bearing block 66 on shaft 42, such that the inner keyway slots 70 overlie the outer keyway slots 64 in a coextensive position. Thus, a pair of key bars 72 can be mounted in the outer keyway slots 64, and the inner keyway slots 70 can be slid along the key bars 72 for mounting the bearing block 66 on shaft 42. The bearing block 66 is axially positioned along shaft 42 by means ofa shim washer 74, and is secured with a thrust washer 76 which is compressed by a threaded nut 78 that is screwed onto the end section 62.

Each of the pulverizer rollers 26 is fabricated with an internal central bearing surface 80 for receiving each of the bearing blocks 66, such that the satellite spacer assembly 40 is supported on the rollers 26 which are in turn rotatably mounted on the shafts 42. As shown in FIG. 2, central bearing surface 80 is oversized, such that the bearing block 66 can be freely mounted in the bearing surface 80. Thus, it can be appreciated that the bearing block 66 can easily be removed for the purpose of replacement as well as reversing the bearing block 66, such that the outer end of bearing block 66 contacts the shim washer 74. This reversing procedure increases the life of the bearing block through obtaining uniform wear.

In the operation of the pulverizing apparatus 10, the satellite spacer assembly 40 affords a means for supporting the shafts 42 on which the rollers 26 are rotatably mounted. In this manner, rollers 26'are separated from each other and are centrally guided around the annular groove 24. The satellite spacer assembly 40 thereby provides superior guidance for the rollers 26 with minimum drag, which accounts for reduced yaw of the rollers 26 about the shafts 42, as well as. reduced 4 skidding of the rollers 26.

A latitude of modification, change and substitution is intended in the foregoing disclosure and in some instances some features of the invention will be employed without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the spirit and scope of the invention herein.

What is claimed is:

1. Apparatus for pulverizing material into comminuted particles comprising a housing, a table having a grinding surface mounted in said housing for rotation,

means for rotating said table, means for introducing said material into said housing in contact with said grinding surface, a plurality of rollers mounted for rotation about their respective axes and each of the rollers having a peripheral grinding face maintained in contact with said table, and spacer means positioned above said table including a center yoke formed with a central opening and spaced apart from said table and a plurality of shafts fixed tosaid center yoke which radially extend outward for rotatably mounting said rollers and supporting said center yoke on said rollers, said center yoke formed in the shape of an annulus, and said shafts mounted along the outer periphery of said annulus, and external bearing means keyed to the ends of said shafts and said rollers formed with an internal bearing surface for receiving said external bearing means, such that said rollers are separated from each other and said rollers are prevent from skidding.

2. Apparatus for pulverizing material into comminuted particles according to claim 1, in which said annulus is formed with a frustoconical configuration such that said shafts are capable of being mounted at an acute angle to the vertical axis of said center yoke.

3. Apparatus for pulverizing material into comminuted particles according to claim 1, in which said bearing means are formed with a spherical external configuration and said internal bearing surface is cylindrically shaped and sized for rotatably mounting said rollers.

4. Apparatus for pulverizing material into comminuted particles according to claim 1, in which the ends of said shafts are formed with a reduced diameter section, external threads are formed on the outer extremity of said reduced diameter sections, and internally threaded nuts are threadably engaged with said external threads for removably securing said bearing means to said shafts.

- UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION T ,790,095 February 5, 1974 Patent No. Dated "Robert Paul Gillette Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the cover sheet insert [731 Assignee: Foster Wheeler Corporation, Livingston, New Jersey Signed and sealed this 14th day of January 1975.

I (SEAL) Attest:

McCOY M. GIBSONVJR. c. MARSHALL DANN Attesting Officer 7 Commissioner of Patents FORM PO-105O (O-G9) 5 c 30 75.

. U,S. GOVERNMENT PR'NTING OFFICE: 

1. Apparatus for pulverizing material into comminuted particles comprising a housing, a table having a grinding surface mounted in said housing for rotation, means for rotating said table, means for introducing said material into said housing in contact with said grinding surface, a plurality of rollers mounted for rotation about their respective axes and each of the rollers having a peripheral grinding face maintained in contact with said table, and spacer means positioned above said table including a center yoke formed with a central opening and spaced apart from said table and a plurality of shafts fixed to said center yoke which radially extend outward for rotatably mounting said rollers and supporting said center yoke on said rollers, said center yoke formed in the shape of an annulus, and said shafts mounted along the outer periphery of said annulus, and external bearing means keyed to the ends of said shafts and said rollers formed with an internal bearing surface for receiving said external bearing means, such that said rollers are separated from each other and said rollers are prevent from skidding.
 2. Apparatus for pulverizing material into comminuted particles according to claim 1, in which said annulus is formed with a frustoconical configuration such that said shafts are capable of being mounted at an acute angle to the vertical axis of said center yoke.
 3. Apparatus for pulverizing material into comminuted particles according to claim 1, in which said bearing means are formed with a spherical external configuration and said internal bearing surface is cylindrically shaped and siZed for rotatably mounting said rollers.
 4. Apparatus for pulverizing material into comminuted particles according to claim 1, in which the ends of said shafts are formed with a reduced diameter section, external threads are formed on the outer extremity of said reduced diameter sections, and internally threaded nuts are threadably engaged with said external threads for removably securing said bearing means to said shafts. 